Glow discharge device



July 11, 1939. R. B. MORGAN 2,1651505 61.0w DISCHARGE DEVICE OriginaiFiled Jan. 6, 1930 INVENT'OR Raymond Bainbridge Margan Patented July 1l, 1939 assignor, by mesne assignments, to Radio Corporation of America,New York, N. Y., a corporation of Delaware Original application January6, 1930, Serial No.

418,920. Divided and this application February 14, 1936, Serial N0.63,963. In Great Britain February 12,1929

2 Claims.

The present invention relates to glow dis-' charge tubes, and moreparticularly to the use of such tubes in the recording or transmittingof mechanical or electrical oscillations with the 5 aid of light, thisapplication being a division of my copending application Serial No.418,920, filed January 6, 1930.

According to the present invention, light, modulated in intensity inaccordance with electrical 10 or mechanical oscillations, is generatedby means of a discharge tube the light from which is magneticallycontrolled or influenced.

The invention further provides a discharge device comprising an envelopecontaining mer- 5 cury vapor and having disposedjtherein a filamentarycathode, an anode surrounding said cathode, and a coil arranged aroundsaid envelope, said filamentary cathode lying substantially along theaxis of said coil.

The invention is illustrated by way of example in the accompanyingdrawing, in which Figs. 1 and 2 show views in part sectional sideelevation and in end elevation respectively of a discharge tube inaccordance with the invention,

as and 0 vapor at a suitable pressure.

Figs. 3 and 4 illustrate diagrammatically two circuit arrangementsaccording to the invention.

Referringto Figs. 1 and 2, an envelope l, which may be of quartz orglass, is filled with mercury 7 Within the envelope l are mounted afilamentary cathode 2 ofhelieal shape and a cylindricaljanode 3 (forexample of nickel) surrounding the cathode 2. Aroundthe outside oi-theenvelope l is 'fixed a 35 coil 4. The filament 2 lies along the axis ofthe coil 4, In this way, ,when current is passed through-the coil 4, amagnetic field is established in the discharge space around the filament2 and parallel to e filamentaxis. The effect 01 this magnetic eld isgreatly tointenslfy the light emitted and to concentrate it in an axialdirec- 'tion. Preferably, the longitudinal axes of the amplification, onthe coil 4. A steady direct cur- (Cl. ire-122) rent is also passedthrough the coil 4 or through. a separate coil arranged coaxiallytherewith. The value of this direct current is so adjusted that thesteady magnetic field produced thereby brings the tube into such a statethat a small change of field strength produces a large change in'thelight emitted in a direction axially of the coil in accordance with alinear'relation. When adjusted in this way, the oscillatory currents inthe coil 4 cause the intensity of the light emitted to varycorrespondingly. These variations in light intensity may be used inknown manner to produce a photographic sound record.

The light is, of course, emitted in a direction axially ofthe coil 4 andis in the form of a cylindrical column of light extending as far as thewall of the envelope.

In the circuit of Fig. 3, the choke coil 5 serves to prevent alternatingcurrents generated hetween the electrodes, 2, 3 of the tube from flowingthrough the anode current source. As shown in dotted lines, theseoscillations may be used with or without amplification to operate amonitoring device such as a loudspeaker 6.

Referring now to Fig. 4, instead of varying the intensity of themagnetic field produced by the coil 4, this field is maintained constantand the light variations are obtained by impressing electricaloscillations upon the electrodes of the tube.v The magnetic field,nevertheless, influences the light emittedby greatly increasing theintensity of the glow. The anode 3 is connected, as before, through achoke coil ,5 to a positive potential point, and the coil fed withdirect current from a source -I, the value of this current beingadjustable by means of the variable resistance 8.

before from a microphone, are impressed upon the primary winding of thetransformer 9 and in this way an alternating potential difference isapplied through the blocking condenser l0 between the two electrodes 2,3 and modulates the steady potential between them.

Although the invention has been described with particular reference tosound recording, it may be'applied to other purposes.

When, for example, the apparatus is used for transmitting oscillationswith the aid of light from one station to another, the lightirom thesending station may be allowed to-fallupon a photo-sensitive device atthe receiving station.

The apparatus may also be used in connection with the receiving'stationof a television or phototelegraphlc system, the incoming electricaloscillations being impressed upon the dischargedevlce Electricaloscillations, which may be derived as tensity of the light emitted. Incombination with -a suitable scanning device, therefore, theapparatus'may be used to build up at the sending station the picture orview transmitted.

The invention may also be applied to the generation of light oi varyingintensity from me-' chanical oscillations without first converting themechanical oscillations into'electrical oscillations.

For example, thefmagnetic field in the discharge space may beestablished by orthrough amemher which is capable of vibration. Themechanical vibrations of this member "can be made to produce variationsin the intensity of the magnetic field around the filament. Clearly,this'can be done either by arranging that the mechanical oscillationsefi'ect a change in the intensity of the magnetic field or else bycausing the mechanical oscillations to change the position oi themagnetic field and thus alter the intensity or .the field around thecathode although theoverall intensity of the field may remain constant.Acombination of these two efiects can also beused. J

It has been found that, after the tube of the type described hascommenced to--glovv the curand producing corresponding changes in theinrent for heating the filament may frequently be interrupted withoutinterfering with the behavior of the tube. The filament may in somecases be replaced by a cold electrode, separate ionizing means beingprovided within the tube to initiate the discharge.

I claim as my invention:

1. A glow discharge device comprising an en-" velope containingmercurygvapor, a helical filamentary cathode disposed in said enevelope,a cylindrical anode surrounding said cathode and having its axissubstantially coincident with that v of said helical cathode, and a coilarranged around said envelope, said cathode lying substantially alongthe axis of said coil.

2. A glow discharge device comprising a cylindrical envelope containingmercury vapor, a helical filamentary cathode disposed in said envelopelongitudinally, thereof, a cylindrical anode sur- 'roundingsaid cathodeand also extending longi-' tudinally in said envelope, and a coilarranged aroundsaid envelope, the axes of said envelope, said helicalcathode, said anode and said coil being substantially coincident. f

' RAYMOND BAINBRIDGE MORGAN.

